Add cache and optimize code

gallery/models/photo.py

@@ -1,6 +1,7 @@
 import os
 from datetime import datetime
 
+from django.core.cache import cache
 from django.db import models
 from django.db.models.signals import post_save
 from django.dispatch import receiver
@@ -47,7 +48,6 @@ class Photo(models.Model):
             self.slug = os.path.basename(self.photo.name)
         super().save(*args, **kwargs)
 
-
     def add_like(self):
         self.likes += 1
         self.save(update_fields=['likes'])
@@ -58,7 +58,7 @@ class Photo(models.Model):
 
     def get_next(self):
         return self.__class__.objects.filter(taken_at__gt=self.taken_at, album=self.album).order_by('taken_at').first()
-
+    
     def get_prev(self):
         return self.__class__.objects.filter(taken_at__lt=self.taken_at, album=self.album).order_by('-taken_at').first()
 
@@ -79,13 +79,19 @@ class Photo(models.Model):
     
 
 
-def create_photo(sender, instance, created, **kwargs):
-    if created:
-        """ Add exif metadata """
+@receiver(post_save, sender=Photo)
+def handle_photo_creation(sender, instance, created, **kwargs):
+    if not created:
+        return
+
+    # Lisää EXIF metadata
+    if instance.photo and instance.photo.path:
         exif = Exif(instance.photo.path)
         instance.exif = exif.data
-        """ Update taken datetime """
         instance.taken_at = exif.datetimeoriginal('Europe/Helsinki')
-        instance.save()
+        instance.save(update_fields=['exif', 'taken_at'])
 
-post_save.connect(create_photo, sender=Photo)
+    # Aseta cover, jos albumilla ei ole vielä sellaista
+    if instance.album and not instance.album.cover:
+        instance.album.cover = instance
+        instance.album.save(update_fields=['cover'])